Local Strategy Improvement for Parity Game Solving

The problem of solving a parity game is at the core of many problems in model checking, satisfiability checking and program synthesis. Some of the best algorithms for solving parity game are strategy improvement algorithms. These are global in nature since they require the entire parity game to be present at the beginning. This is a distinct disadvantage because in many applications one only needs to know which winning region a particular node belongs to, and a witnessing winning strategy may cover only a fractional part of the entire game graph. We present a local strategy improvement algorithm which explores the game graph on-the-fly whilst performing the improvement steps. We also compare it empirically with existing global strategy improvement algorithms and the currently only other local algorithm for solving parity games. It turns out that local strategy improvement can outperform these others by several orders of magnitude

Vibration Reduction and Performance Enhancement in Rotorcraft Using Active Flaps at High Advance Ratios

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76329/1/AIAA-2006-1861-222.pd

Adaptive Harmonic Steady-State Control for Disturbance Rejection

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57793/1/HSSTCSTNov2006.pd

Higher-Harmonic-Control Algorithm for Helicopter Vibration Reduction Revisited

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57823/1/HHCJGCD2005.pd

G_2 Domain Walls in M-theory

M-theory is considered in its low-energy limit on a G_2 manifold with non-vanishing flux. Using the Killing spinor equations for linear flux, an explicit set of first-order bosonic equations for supersymmetric solutions is found. These solutions describe a warped product of a domain wall in four-dimensional space-time and a deformed G_2 manifold. It is shown how these domain walls arise from the perspective of the associated four-dimensional N=1 effective supergravity theories. We also discuss the inclusion of membrane and M5-brane sources.Comment: 30 pages, Late

The HHC Algorithm for Helicopter Vibration Reduction Revisited

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76087/1/AIAA-2004-1948-209.pd

Stable Topologies of Event Horizon

In our previous work, it was shown that the topology of an event horizon (EH) is determined by the past endpoints of the EH. A torus EH (the collision of two EH) is caused by the two-dimensional (one-dimensional) set of the endpoints. In the present article, we examine the stability of the topology of the EH. We see that a simple case of a single spherical EH is unstable. Furthermore, in general, an EH with handles (a torus, a double torus, ...) is structurally stable in the sense of catastrophe theory.Comment: 21 pages, revtex, five figures containe

An Aerothermoelastic Analysis Framework Enhanced by Model Order Reduction With Applications

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143034/1/6.2017-1601.pd

Thermal Stability and Rehybridization of Carbon Bonding in Tetrahedral Amorphous Carbon

We preform a quantitative investigation of the energetics of thermally induced sp3 → sp2 conversion of carbon-carbon bonds in tetrahedral amorphous carbon (ta-C) films by using near edge x-ray absorption fine structure (NEXAFS) and Raman spectroscopy. We investigate the evolution of the bonding configuration in ta-C thin films subjected to high temperature annealing in flowing Argon gas using a rapid thermal annealing furnace over the range of 200-1000 ºC. We observe no substantial change in bonding structure below 600 ºC, and by 1000 ºC a significant increase in the sp2 bonding in the film is observed. No oxygen bonding is detected in the NEXAFS spectra, but we do observe an isosbestic point, demonstrating that the thermally driven sp3 → sp2 conversion reaction occurs without passing through an intermediate transition state. This allows us to use NEAFS spectra of thermally annealed ta-C films to quantitatively determine that the activation energy for directly converting the sp3-bonded carbon to the s